- cloud computing
- IaaS
- PaaS
- SaaS
- shared responsibility
- elasticity
- pay-as-you-go
The Cloud — Renting Computers Instead of Owning Them ☁️
Demystified in one sentence: "the cloud" is just someone else's computers, rented over the internet, that you pay for by the hour instead of buying. That is it. No magic — your EcoFinLearn site runs on rented machines you have never seen, in a building you will never visit.
🧠 The mental model: electricity
You do not run a diesel generator in your basement to power your laptop — you plug into the grid and pay for what you use. The cloud did the same thing to computing: instead of buying servers (capital, maintenance, a room with air-con), you plug into AWS / Azure / Google Cloud and pay for what you use. Need 100 servers for an hour? Done. Finished with them? Stop paying.
The 3 layers: IaaS, PaaS, SaaS
This is the model everyone is expected to know. The difference is how much you manage vs how much the provider manages:
| Layer | You rent... | You manage... | Example |
|---|---|---|---|
| IaaS (Infrastructure) | raw virtual machines | the OS, runtime and your app | AWS EC2 |
| PaaS (Platform) | a managed platform | just your app code | Vercel, Heroku |
| SaaS (Software) | finished software | nothing — you just use it | Gmail, Slack |
🍕 The pizza analogy that locks it in: IaaS = you buy the ingredients and use their oven. PaaS = pizza delivered, you supply the table and drinks. SaaS = you walk into the restaurant and just eat. The higher up the stack, the less you cook.
Two superpowers: elastic + pay-as-you-go
- ›Elasticity — scale up for a traffic spike, scale back down at midnight, automatically.
- ›Pay-as-you-go — no upfront server purchase; you are billed per second / per GB used.
⚠️ The flip side: pay-as-you-go cuts both ways. A server you forgot to turn off bills you all month. Cloud cost control ("FinOps") is a real job precisely because it is so easy to leave the meter running.
The shared-responsibility model (the security bit)
A rule that trips up every newcomer: the provider secures the cloud itself (data centres, hardware), but you secure what you put in it (your data, your access keys, your configuration). Most cloud breaches are misconfigured customer settings — not the provider being hacked.
🔧 You already use it
EcoFinLearn is deployed on Vercel — a PaaS. You push code; Vercel runs it on rented infrastructure, scales it, and serves it globally. You manage your app; they manage the platform. That is the cloud, and you are already living it.
Your Task
Tag a list of real services with the cloud layer you operate at — and print how much you have to manage for each.